Search for Event Rate Modulation in XENON100 Electronic Recoil Data.

Area of Science:

• Particle Physics
• Astroparticle Physics
• Dark Matter Research

Background:

• The search for dark matter often involves looking for periodic signals, such as annual modulations, in detector event rates.
• Previous experiments have reported potential signals, but independent verification is crucial.

Purpose of the Study:

• To search for periodic variations in the electronic recoil event rate within the XENON100 detector.
• To test the hypothesis of dark matter interactions causing such modulations.
• To exclude or confirm specific dark matter models, including those suggested by DAMA/LIBRA.

Main Methods:

• Analysis of 224.6 live days of XENON100 data (February 2011 - March 2012) in the 2-6 keV energy range.
• Detailed detector stability and background contribution assessment.
• Unbinned profile likelihood analysis for periodicity up to 500 days.

Main Results:

• No statistically significant global periodicity (less than 1σ) was found in the electronic recoil event rate.
• A local annual modulation signal (2.8σ) was observed but disfavored as dark matter due to control sample analysis and phase.
• The DAMA/LIBRA annual modulation signal is excluded at 4.8σ for a specific dark matter model (WIMP-electron axial-vector coupling).

Conclusions:

• The XENON100 data shows no evidence for periodic modulations attributable to dark matter.
• The findings challenge dark matter interpretations of the DAMA/LIBRA annual modulation signal.
• Further investigation with more sensitive detectors is needed to confirm or refute dark matter signals.